The invention relates to a system for coating, in particular painting, objects, in particular vehicle bodies, having                a) a coating booth in which the objects may be acted upon by coating material and through which an air stream can be conducted which takes up the overspray particles of the coating material and conveys them away;        b) an electrostatically operating separating device whereof the housing has an inlet opening for the overspray-particle-laden air and an outlet opening for the cleaned air, wherein at least one separating electrode, which has a separating surface, and a counter electrode device are arranged in the housing;        c) a high voltage source whereof the poles may be connected to the separating electrode or the counter electrode device;        d) an air path for the overspray-particle-laden air, which leads from the base of the coating booth to the inlet opening of the separating device.        
When paints are applied manually or automatically to objects, a substream of the paint, which generally contains both solid bodies as well as solvent and/or binding agent, does not reach the object. This substream is known among experts as “overspray”. The overspray is taken up by the air stream in the coating booth and supplied for separation so that, if required, the air can be conducted back to the coating booth after suitable conditioning.
Particularly in systems with a relatively high paint consumption, for example in systems for painting vehicle bodies, wet separation systems are preferably used. In commercially known wet separators, water flows together with the booth exhaust air coming from above to a nozzle accelerating the air stream. A swirling of the through-flowing booth exhaust air with the water takes place in this nozzle. During this procedure, the overspray particles largely pass over into the water so that the air exiting the wet separator has been substantially cleaned and the paint overspray particles are located in the water. They can then be recovered from this or disposed of. In known wet separators, a relatively high amount of energy is needed to circulate the very large quantities of water required and to overcome the pressure differences between booth, nozzle and disposal area. Treating the rinsing water is costly due to the elevated use of paint-binding and detackifying chemicals and the disposal of paint sludge. Furthermore, as a result of the intensive contact with the rinsing water, the air absorbs a great deal of moisture which, in recirculating-air mode, in turn leads to a high energy consumption for treating the air or, with a high moisture or solvent content, means that the exhaust air has to be rejected.
In contrast, in commercially known devices of the type mentioned at the outset, a dry separation process is used in that paint overspray particles which are entrained by the booth air flowing past are ionised by the counter electrode device of the electrically operating separating device and, owing to the electrical field established between the separating electrode and the counter electrode device, migrate to the separating surface of the separating electrode, on which they are separated.
In known systems of the type mentioned at the outset, the overspray particles adhering to the separating surface are stripped off this mechanically and transported away.